<template>
    <div class="son">
        <h3>子组件</h3>
        <input type="text" @input="e => countvalue = e.target.value" :value="countvalue">
    </div>
</template>

<script setup>
import { defineModel } from 'vue'
const countvalue = defineModel()

</script>

<style>
.son {
    border: 1px solid red;
    width: 200px;
    height: 200px;
}
</style>